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Date: Wed, 23 Aug 2023 07:37:43 -0700
From: Rita Zhang <rita.z.zhang@...il.com>
To: oss-security@...ts.openwall.com
Subject: [kubernetes] CVE-2023-3893: Insufficient input sanitization on
kubernetes-csi-proxy leads to privilege escalation
Hello Kubernetes Community,
A security issue was discovered in Kubernetes where a user that can create
pods on Windows nodes running kubernetes-csi-proxy may be able to escalate
to admin privileges on those nodes. Kubernetes clusters are only affected
if they include Windows nodes running kubernetes-csi-proxy.
This issue has been rated ***HIGH*** (
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
<https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H>
-
8.8
<https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H>),
and assigned **CVE-2023-3893**
*Am I vulnerable?*
Any kubernetes environment with Windows nodes that are running
kubernetes-csi-proxy is impacted. This is a common default configuration
on Windows nodes. Run `kubectl get nodes -l kubernetes.io/os=windows`
<http://kubernetes.io/os=windows> to see if any Windows nodes are in use.
*Affected Versions*
- kubernetes-csi-proxy <= v2.0.0-alpha.0
- kubernetes-csi-proxy <= v1.1.2
*How do I mitigate this vulnerability?*
The provided patch fully mitigates the vulnerability and has no known side
effects. Full mitigation for this class of issues requires patches applied
for CVE-2023-3676, CVE-2023-3955, and CVE-2023-3893.
Outside of applying the provided patch, there are no known mitigations to
this vulnerability.
*Fixed Versions*
- kubernetes-csi-proxy v2.0.0-alpha.1
- kubernetes-csi-proxy v1.1.3
These releases will be published over the course of today, August 23rd,
2023.
To upgrade: cordon the node, stop the associated Windows service, replace
the csi-proxy.exe binary, restart the associated Windows service, and
un-cordon the node. See the installation docs for more details:
https://github.com/kubernetes-csi/csi-proxy#installation
If a Windows host process daemon set is used to run kubernetes-csi-proxy
such as
https://github.com/kubernetes-csi/csi-driver-smb/blob/master/charts/latest/csi-driver-smb/templates/csi-proxy-windows.yaml,
simply upgrade the image to a fixed version such as
ghcr.io/kubernetes-sigs/sig-windows/csi-proxy:v1.1.3
*Detection*
Kubernetes audit logs can be used to detect if this vulnerability is being
exploited. Pod create events with embedded powershell commands are a strong
indication of exploitation.
If you find evidence that this vulnerability has been exploited, please
contact security@...ernetes.io
*Additional Details*
See the GitHub issue for more details:
https://github.com/kubernetes/kubernetes/issues/119594
*Acknowledgements*
This vulnerability was discovered by James Sturtevant @jsturtevant and Mark
Rossetti @marosset during the process of fixing CVE-2023-3676 (that
original CVE was reported by Tomer Peled @tomerpeled92)
The issue was fixed and coordinated by the fix team:
James Sturtevant @jsturtevant
Mark Rossetti @marosset
Andy Zhang @andyzhangx
Justin Terry @jterry75
Kulwant Singh @KlwntSingh
Micah Hausler @micahhausler
Rita Zhang @ritazh
and release managers:
Mauricio Poppe @mauriciopoppe
Thank You,
Rita Zhang on behalf of the Kubernetes Security Response Committee
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